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OBDII INSPECTION GUIDE

Texas Department of Public Safety

September 2002

Prepared by:

dKC de la Torre Klausmeier Consulting, Inc.

2002 dKC

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Table of Contents

GLOSSARY OF OBD TERMS ..................................................................................2

INTRODUCTION....................................................................................................12

MOTOR VEHICLE CONTRIBUTION TO AIR POLLUTION IN TEXAS.......................12

OBD INSPECTION PROCEDURE...........................................................................13

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GLOSSARY OF OBDII TERMS

Catalyst Monitor

The hardware and software used to monitor the conversion efficiency of the catalytic converter

(see definition of monitor).

The three-way catalytic converter is used to convert the primary exhaust pollutants (HC, CO and

NOx) into carbon dioxide (CO2), water (H2O) and nitrogen. During the conversion process,

NOx gas is separated into nitrogen and oxygen. The oxygen is used for the secondary oxidationof HC and CO into H2O and CO2. The nitrogen exits as a non-reactive gas.

The cat monitor diagnoses the catalytic converter by comparing the signal between the upstreamand downstream oxygen sensors (HO2S). A correctly operating cat system will show slight

swings in oxygen sensor voltage for the downstream sensor, while wide swings are found in the

upstream sensor.

The catalytic converter is monitored on a non-continuous basis, after the vehicle completes anappropriate drive cycle. The cat monitor is usually executed once per trip.

Comprehensive Components Monitor

The hardware and software used to monitor electronic components.

The on-board system must check for malfunctions in any electronic component or system thateither provides input to, or receives commands from the PCM for emissions control. These

components or systems are referred to as comprehensive components. Like fuel trim,

comprehensive components are continuously monitored.

Sensor inputs are to be tested for, at a minimum, lack of circuit continuity and rationality (out of

range values). Lack of circuit continuity includes any type of electrical circuit fault, (open

circuit, short to voltage or ground) switch or sensor failures, (opens, internal shorts, shorts toground or voltage) and PCM internal problems.

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The Throttle Position Sensor will be used as an example of a rationality check. If the engine

speed is high, engine load indication is high and airflow is high, but the Throttle Position signal

indicates a closed throttle condition, then the OBDII system must detect the fault and set an

appropriate DTC.

DLCData Link Connector. This is the physical connector/electrical interface between the vehicle'son-board computer system and off-board diagnostic equipment. The DLC is required to be

located between the drivers end of the instrument panel and approximately one foot beyond the

vehicle centerline, on or below the instrument panel. On most vehicles, the connector is locatedbeneath the instrument panel, near the steering column. Also, on most vehicles the connector is

exposed, but on some vehicles the connector is behind a small panel which must be opened to

gain access. On a few vehicles, the connector may be more difficult to locate.

DTC

Diagnostic Trouble Code. Trouble codes are how OBDII identifies and communicates to

technicians where and what on-board problems exist. The first number in the DTC indicateswhether the code is an SAE standard code (applies to all OBDII systems) or is specific to the

vehicle manufacturer. The remaining three numbers provide information regarding the specific

vehicle system and circuit. An analysis of a typical OBDII code is shown below.

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EGR Monitor

The hardware and software used to monitor the Exhaust Gas Recirculation (EGR) system (see

definition of monitor).

The purpose of an EGR system is to lower combustion chamber temperature, thereby reducing

NOx emissions. The EGR system recirculates non-combustible exhaust gases back into thecylinder to dilute the incoming air/fuel charge. This process reduces temperatures in thecombustion chamber. By lowering combustion temperatures, NOx emissions are reduced.

Besides creating excessive NOx emissions, high combustion chamber temperatures can cause the

fuel to ignite prematurely. This results in spark knock and can lead to serious engine damage.

The components of the EGR system include:

EGR Valve

EGR Solenoid

EGR Backpressure Tube

Electronic EGR Transducer (EET) Connecting Hoses

The EGR system on OBDII equipped vehicles is monitored for high and low flow rates and otherparameters. If the EGR monitor fails the system check, the Malfunction Indicator Lamp (MIL)

will illuminate and a DTC with Freeze Frame data will be stored. The EGR system is monitored

on a non-continuous basis, after the vehicle completes an appropriate drive cycle.

Enabling Conditions

These are specific circumstances that must occur in order for a monitor to run.

EVAP MonitorThe hardware and software used to monitor the evaporative emissions control (EVAP) system

(see definition of monitor).

The purpose of the EVAP system is to prevent the release of hydrocarbon (HC) vapors into the

atmosphere. Fuel vapors from the tank are stored in a charcoal canister until the PCMcommands that the system be purged. Small leaks in the EVAP system can increase evaporative

emissions by a factor of 30 or more. OBDII systems must monitor the EVAP system.

The EVAP monitor is designed to detect a level of HC loss equal to or greater than an opening in

the system of 0.040 inch in diameter. By 2004, all vehicles must detect a HC loss equal to or

greater than an opening in the system of 0.020 inch in diameter. Additionally, the EVAPmonitor is used to verify proper airflow throughout the system. The MIL will illuminate and aDTC will be stored when potential problems are detected. Loose gas caps are a frequent cause of

MIL illumination. The EVAP system is monitored on a non-continuous basis, after the vehicle

completes an appropriate drive cycle.

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Freeze frame

OBDII regulations require that when an emissions related malfunction occurs, vehicle-operating

parameters are to be stored in the powertrain control module (PCM-OBDII terminology for the

onboard computer). This is typically referred to as freeze frame data. Only emissions relatedDTCs are stored in freeze frames. The specific engine parameters that are recorded include, but

are not limited to, the following:

engine rpm

vehicle speed

air flow

engine load

fuel pressure

fuel trim value (i.e., rich or lean)

engine coolant temperature

intake manifold pressure

open or closed loop status

Freeze frame data can be valuable to technicians because they record the conditions during

which the engine system malfunctioned.

Fuel System MonitorThe hardware and software used to monitor the fuel metering system (see definition of monitor).

Using feedback from the oxygen and other sensors, the PCM manages the fuel system tooptimize engine combustion conditions. OBDII regulations require that the fuel system be

continuously monitored. The MIL is to be illuminated if fuel system cannot be controlled by the

PCM.

KOEO

Key On Engine Off, a specific state of the vehicle where the ignition key is turned to the onposition but the engine is not started. When the vehicle is in the KOEO state, the inspector can

check to see if the MIL bulb is working.

KOER

Key On Engine Running, a state of the vehicle where the engine has been started and allowed to

run. OBDII system download and a visual check of the MIL occurs during the KOER state.

Malfunction

The inability of an emissions-related component or system to remain within design

specifications.

Further, malfunction refers to the deterioration of any of the (emission) components or systems

to a degree that would likely cause the emissions of an average vehicle to exceed the emissionsstandards by 1.5 % times.

MIL

Malfunction Indicator Lamp (MIL) is a term used for the light on the instrument panel, whichnotifies the vehicle operator of an emission related problem. The MIL is required to display the

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phrase check engine or service engine soon. The ISO engine symbol also may be used as a

substitute for the word engine.

The MIL illuminates when a failure occurs which could cause vehicle emissions to exceed 1.5times their designed standard. The MIL also illuminates when a problem is detected in a

component that is used as part of the diagnostic strategy for any other monitored system orcomponent. The purpose of the MIL is to alert the driver to the malfunction so service can beperformed in a timely manner.

The MIL can only be used to indicate actual problems in the emissions control system. It cannotbe used as a maintenance reminder, e.g., change oil.

Illumination of the MIL is subject to the following conditions:

When severe misfire occurs that could damage the catalytic converter, the MIL isrequired to flash on and off once per second. Flashing is intended to discourage vehicle

operation.

Constant illumination of the MIL (i.e., it is not flashing) indicates that a problem hasbeen detected and the vehicle should be serviced as soon as possible.

The vehicle onboard diagnostic system can turn the MIL off if the problem does not reoccur for

three consecutive trips. For some monitors, the vehicle must be operated under similar

conditions to those that occurred when the vehicle originally illuminated the MIL before the MILcan be turned off.

Misfire Monitor

The hardware and software used to detect engine misfire (see definition of monitor).

Engine misfire is a condition that results from either a lack of combustion (total misfire), or an

instability that occurs during the combustion process (partial misfire). When an engine misfires,raw fuel enters the exhaust. This situation not only raises hydrocarbon emissions, but the

temperature of the catalytic converter as well. Monitoring misfires and identifying offending

cylinders is a requirement of OBDII. This is typically accomplished by monitoring crankshaftdeceleration. The monitor looks for a change in crankshaft speed as indicated by a change in the

pulse width or frequency outputted by the crankshaft position sensor. Misfire is monitored

continuously.

Monitors

A principal part of a vehicles OBDII system is the diagnostic monitors. These are periodic tests

run on specific systems and components to ensure that they are performing within theirprescribed range. The OBDII inspection consists of checking the results of the continuous

self-tests that have occurred while the vehicle was driven prior to the time of inspection. Unlike

a tailpipe test, the vehicle does not have to be warmed-up or pre-conditioned to perform an

OBDII inspection,.

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Most diagnostic monitors do not turn the MIL on when the vehicle fails a test for the first time.

Instead a pending code is set along with the corresponding freeze frame data. If the test fails

on a second consecutive trip, however, the MIL is illuminated and a DTC is stored.

Continuous Monitors -- Some of the vehicle components or systems are continuouslytested by the vehicles OBDII system, while others are tested only under specific vehicleoperating conditions. The continuously monitored components listed below are always

ready:

Misfire

Fuel System

Comprehensive Components

Once the vehicle is running, the OBDII system is continuously checking the above

components, monitoring key engine sensors, watching for engine misfire, and monitoring

fuel demands. For example, if a wire on the throttle position sensor were to break, theOBDII system would "see" the fault and command the MIL on.

Non-Continuous Monitors -- Unlike the continuous monitors, many emissions and

engine system components require the vehicle to be operated under specific conditions

before the monitor is ready (see definition of readiness). These monitors are termed non-continuous monitors and are listed below:

EGR System

02 Sensors

Catalyst

Evaporative System Others if vehicle is so equipped (secondary air system, heated catalyst, and

A/C system)

On board diagnostics (OBD)

A program that assesses the condition of the system, including the sensors and the computer

itself and communicates its findings to the technician by means of diagnostic trouble codes.

Early (pre-1996) Onboard Diagnostic Systems - To assist technicians in diagnosing

problems in electronically controlled engine systems, manufacturers equipped them with

onboard diagnostics (OBD). The first OBD systems appeared on 1980 model year

vehicles. These systems are often referred to as OBDI technology. Although OBDIsystems were not standardized, most OBDI systems were designed to monitor fuel,

ignition, and emissions system components to determine if they are operating correctly.

When a system was found to be operating out of specification, a fault code was stored inthe computer. In some cases, a check engine light illuminates. Technicians could

connect to the computer through a diagnostic link connector (DLC) and download fault

codes.

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Despite the advantages offered by the OBDI systems, they presented several practical

problems in actual use:

The DLC connectors were not standardized. Technicians need a wide variety of

interfaces to properly connect to OBDI systems on different vehicles. Fault codes were not consistent among vehicle manufacturers. Technicians need

vehicle specific information to be able to interpret the results of OBDI tests.

Names for different emission control and engine systems were not standardized.Technicians must be familiar with vehicle specific terminology.

The criteria to illuminate the check engine light or malfunction indicator light(MIL) was not consistent among the vehicle manufacturers.

The type of information stored to assist technicians in diagnosing problems in thevehicles varied significantly among the different manufacturers.

OBDII Systems Recognizing the importance of onboard diagnostic systems in

maintaining the emission control performance of a vehicle, the federal governmentestablished regulations that required all vehicles to meet specific and consistent

requirements for OBD systems. This second generation of onboard diagnostics is termed

OBDII. This second generation was phased in starting in model year 1994 and by the1996 model year; all light-duty vehicles sold in the United States met OBDII standards.

The primary purpose of OBDII is to insure that vehicles emit the minimum amount of

pollutants through their useful life.

OBDII regulations require manufacturers to equip vehicles with onboard diagnostic

systems that have the following features:

Standardized protocols for communicating with offboard diagnostic equipment(scan tools) through a standardized diagnostic link connector (DLC) located in aneasily accessible location

Standardized terminology for vehicle emission control components

Standardized diagnostic trouble codes (DTCs)

Freeze frame -- automatic storing of engine parameters at the time that a DTC isset

Standardized requirements for illumination of the malfunction indicator light(MIL) when malfunctions occur which could cause emissions to increase

Determination and recording of readiness status of emission control systemmonitors

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Oxygen Sensor Monitor

The hardware and software used to monitor the oxygen sensor (see definition of monitor).

The oxygen sensors used on an OBDII system have distinct roles. The pre-cat oxygen sensor(s)is used for fuel control, while the post-cat oxygen sensor is used to monitor the performance of

the catalytic converter.

The Oxygen Sensor Monitor consists of two tests which involve both pre-cat and post-cat

sensors:

Sensor signal test

Sensor heater test

The PCM monitors the oxygen sensor's signal when the sensor is at operating temperature. Inthis test, the amplitude and response of the sensor output is checked. The MIL is illuminated if

amplitude and response do not meet minimum criteria.

The PCM checks the performance of the oxygen sensor's heating element to assure that it isheating the sensor during cold start conditions.

Results of both tests are recorded in the PCM. Oxygen sensors are monitored on a non-continuous basis, after the vehicle completes an appropriate drive cycle.

PCM

Powertrain Control Module the on-board computer controlling the engine systems. Some

vehicles may have electronic transmission functions as part of the PCM responsibilities.

Readiness StatusOBDII systems must indicate whether or not the onboard diagnostic system has monitored each

component. Components that have been diagnosed are termed ready, meaning they were tested

by the OBDII system. The purpose of recording readiness status is to allow inspectors todetermine if the vehicles OBDII system has tested all the components and/or systems.

The powertrain control module (PCM) sets a monitor to ready after an appropriate drive cyclehas been performed within one key-on, engine-run, key-off cycle. The drive cycle that enables a

monitor and sets readiness codes to ready varies for each individual monitor. Once a monitor

has been set to ready, it will continue to indicate ready unless the vehicles battery isdisconnected or codes are cleared, with a few exceptions. After a vehicle is repaired (and DTCs

are cleared) or if the battery or PCM has been disconnected, the Readiness Status for each non-

continuous diagnostic monitor will be Not Ready. THIS MEANS THAT THE VEHICLE

MUST BE OPERATED THROUGH A COMPLETE DRIVE CYCLE BEFORE IT CAN BEREINSPECTED.

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Normally, the readiness status of all components or systems will be ready. However, if the

vehicles battery has been recently disconnected, or if DTCs have been recently cleared with ascan tool, all non-continuous components or systems will be set to not ready. Also, if the

driving habits of the vehicle owner or environmental conditions are such that an appropriate

drive cycle has not been completed, that monitor will not be ready. As an example, the catalytic

converter will generally only be monitored when the vehicle is fully warm, at highway speed,and under light load. A vehicle that never sees these conditions will never be ready, since the cat

monitor will never run.

SAE

Society of Automotive Engineers an organization that sets standards and promotes research for

the automotive industry.

Scan tool

A hand held computer that is plugged into a vehicles data link connector allowing the technician

to read diagnostic trouble codes, freeze frame data and other information.

Secondary Air Injection Monitor

The hardware and software used to monitor the secondary air injection system (see definition ofmonitor).

About one-fourth of the vehicles are equipped with air injection systems. These systems injectair into the exhaust manifold while the engine is warming up to reduce cold start emissions. If

the vehicle is equipped with an air injection system then this system must be monitored for

proper operation.

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Sensor

An electrical device used to provide a computer with input information about engine operating

parameters.

Trip

Vehicle operation (following an engine off period suitable to power down the PCM) of durationand driving mode such that a component and system is monitored at least once by the diagnosticsystem.

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OBDII INSPECTION GUIDE

INTRODUCTION

On-board diagnostic systems (OBDII) on 1996 and newer vehicles will be checked aspart of Texas annual vehicle inspection program. OBDII systems were mandated tohelp technicians diagnose and service the computerized engine management systemsof modern vehicles. OBDII systems monitor all components that make up the enginemanagement system. They can detect malfunctions or deterioration of thesecomponents usually well before the motorist becomes aware of any problem. When aproblem that could cause a significant increase in emissions is detected, the OBDsystem turns on a dashboard warning light to alert the driver of the need to have thevehicle checked by a repair technician. All 1996 and newer vehicles use the same typeof connector, use common computer "languages" and use the same criteria for

evaluating the powertrain systems and indicating problems to the driver and the repairtechnician.

OBDII technology benefits motorists, technicians, and our environment. Its good formotorists because it monitors the vehicles performance every time it is driven andidentifies problems immediately, allowing service to be done before more seriousproblems develop. Its good for technicians because it helps them accurately diagnoseproblems, allowing for efficient and proper repairs. And its good for our environmentand our health because it identifies problems that cause vehicle emissions to increase.The purpose of this manual is to familiarize motor vehicle inspectors with how to inspectOBDII systems and what it means when a vehicle fails the inspection.

MOTOR VEHICLE CONTRIBUTION TO AIR POLLUTION IN TEXAS

Motor vehicles emit toxic air pollutants and contribute to the formation of ground levelozone. A 'typical' vehicle emits a half ton of air pollution annually. A malfunctioningvehicle emits many times that amount.

Motor vehicle related smog (ground-level ozone) damages lung tissue and aggravatesrespiratory disease. Ozone is formed by atmospheric reactions between hydrocarbons(HC) and oxides of nitrogen (NO x). Motor vehicles are the largest source of HC and NO x

in Texas. Motor vehicles also are the largest source of toxic compounds in Texas. Toxiccompounds emitted by mobile sources threaten human health even at very low levels.

In addition to direct effects, air pollution from motor vehicles contributes to the formationof acid rain and global warming.

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The number of vehicles and miles driven has doubled in the last 20 years. Over 100billion vehicle miles are driven annually in Texas. So even though todays new cars arecleaner, there are more of them and they are driven more miles. The primary purpose ofOBDII is to insure that vehicles emit the minimum amount of pollutants through theiruseful life.

OBD INSPECTION PROCEDURE

The OBDII inspection consists of checking the results of the self-tests that haveoccurred while the vehicle was driven before the time of inspection. Unlike a tailpipetest, the vehicle does not have to be warmed-up or pre-conditioned to perform anOBDII inspection, The Texas OBDII test procedure consists of the following:

1. Determine Applicability

Confirm that vehicle is model year 1996 or newer gasoline powered vehicles with a

GVWR. (gross vehicle weight rating) of 8,500 pounds or less. OBDII systems werephased in starting in model year 1994, and by the 1996 model year all light-dutyvehicles sold in the United States met OBDII standards.

2. Connect the Inspection System to the vehicles OBD system

With the ignition key off, locate the vehicles diagnostic link connector (DLC) andplug the OBDII test lead into DLC.

All 1996 and newer vehicles are equipped with a standardized diagnosticconnector. This is to allow a generic inspection tool to be used on all OBDII

equipped systems. Inspectors must connect the inspection system to the DLC anddownload information from the OBDII system.

The DLC is required to be located between the drivers end of the instrument paneland approximately one foot beyond the vehicle centerline, on or below theinstrument panel. On most vehicles, the connector is located beneath theinstrument panel, near the steering column. Also, on most vehicles the connectoris exposed. Some vehicles have hard to find DLCs; the connector is behind asmall panel which must be opened to gain access or in a non-standard location.Information on hard-to-find DLCs will be provided to inspection stations in aseparate manual.

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Typical DLC Location

Not So Typical DLC Location

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3. Visual Inspection of Malfunction Indicator Light (MIL)

a. Determine if the instrument panel Malfunction Indicator Light (MIL) illuminateswhen the ignition key is turned to the key on, engine off position. Theinspector will be given the following prompt:

TURN THE IGNITION KEY TO THE ON POSITION, BUT DONT START THEENGINE. LOCATE THE MIL (MALFUNCTION INDICATOR LIGHT) ON THEDASHBOARD. (This is termed the key-on engine-off, KOEO test)

DID THE MIL TURN ON? Note: MIL may stay on continuously or go outafter only a few seconds. (CHOOSE THE CORRECT SENTENCE)

YES, the MIL did come on.

NO, the MIL did NOT come on at all.

The Malfunction Indicator Light (MIL) is the official term for the warning light that isilluminated by the vehicles OBD system when a malfunction occurs. Dependingon the vehicle make, the MIL may display any of the following: Service EngineSoon, Check Engine, the international engine symbol along with the wordCheck, or some combination of these.

Typical MIL Symbols

The MIL illuminates when a failure occurs which could cause vehicle emissions toexceed 1.5 times their designed standard. The purpose of the MIL is to alert thedriver to the malfunction so service can be performed in a timely manner.

The MIL must come on when the ignition key is turned to the key on, engine offposition. This is to allow technicians to check that the MIL is capable of illuminatingif a malfunction were to occur. On most vehicles, the MIL will stay illuminated aslong as the key is in the key on, engine off position. However, on some vehicles,e.g., Chryslers and Hondas, the MIL will illuminate very briefly when the key isturned to the key on, engine off position and then will go out. This is acceptable.

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Be sure to be watching for the MIL to illuminate when you turn the key to the keyon, engine off position, or you may miss it.

b. Start the engine and allow it to idle. Determine if the MIL is illuminated while theengine is running. The inspector will be given the following prompt:

DID THE MIL TURN OFF? (CHOOSE THE CORRECT SENTENCE) (This istermed the key-on engine-running, KOER test)

Yes, the MIL turned off.

No, the MIL stayed on.

If the MIL is on while the engine is running, the vehicles OBD system hasdetermined that there is a problem with the vehicle. In this case, there should beone or more diagnostic trouble codes (DTCs) stored in the vehicles computer.

4. OBDII System Download

Start the engine and allow it to idle. Test system will communicate with on-boardcomputer. If communication cannot be established, system will prompt inspector torecheck connection and try again. After communication is made, test systemautomatically does the following:

Downloads readiness codes -- OBDII systems must indicate whether ornot the onboard diagnostic system has monitored each component.Components that have been diagnosed are termed ready, meaning theywere tested by the OBDII system.

The purpose of the readiness status check is to determine if the vehiclesOBD system has tested all emissions control components or systems.Some of the components or systems are continuously tested by thevehicles OBD system, while others are tested only under specific vehicleoperating conditions. Once testing of a component or system by thevehicles OBD system is complete, the readiness status for that particularcomponent or system will be set to ready.

Normally, the readiness status of all components or systems will beready. However, if the vehicles battery has been recently disconnected,or if diagnostic trouble codes (DTCs) have been recently cleared with ascan tool, components or systems will be set to not ready.

The powertrain control module (PCM-OBDII terminology for the onboardcomputer) sets a monitor to ready after an appropriate drive cycle hasbeen performed. Normal driving usually sets a monitor to ready in a

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couple of days. The dealer or qualified technician has the best informationon how to get a vehicle ready.

Downloads MIL status and diagnostic trouble codes (DTCs) -- Thepurpose of checking MIL status using the inspection system is to

determine if the vehicles OBD system has commanded the MIL to turn onbased on a malfunction. This allows you to determine if there is amalfunction, even if the MIL is not actually illuminated because of aproblem with the MIL itself, or due to tampering with the MIL. If the MIL iscommanded-on, the system will download diagnostic trouble codes(DTCs.) DTCs describe the specific problem identified by the OBDIIsystem (see definition in glossary).

If the system fails to communicate, the inspector will be given the followingprompt:

THE OBD II CONNECTION CANNOT BE CONFIRMED CHOOSE THE NEXTACTION

1. BACK TO PREVIOUS SCREEN

2. CONNECTOR CANNOT BE LOCATED

3. CONNECTOR IS MISSING, DAMAGED, OR TAMPERED.

4. CONNECTOR IS OBSTRUCTED OR INACCESSIBLE AND CONNECTIONIS NOT POSSIBLE.

5. COMMUNICATION FAILED, AND OBD II PORT IS ATTACHED TOCONNECTOR.

PASS/FAIL CRITERIA

If any of the following conditions are met, the vehicle fails the OBD inspection, and theowner or operator must be advised to have the vehicle serviced:

1) The MIL does not illuminate at all when the ignition key is turned to thekey on, engine off position.

A vehicle fails the inspection if the MIL does not illuminate when the ignition keyis turned to the key on, engine off, because the vehicles OBD system cannotalert the driver to a problem when it detects a malfunction.

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2) The MIL is illuminated while the engine is running.

The reason this is a failure is because the vehicles OBDII system has detected amalfunction and turned on the MIL to alert the driver. If the MIL is on while theengine is running, the vehicles OBDII system has determined that there is a

problem with the vehicle. In this case, there should be one or more diagnostictrouble codes (DTCs) stored in the vehicles computer.

3) The MIL status, as indicated by the scan tool, is ON.

The reason this is a failure is because the vehicles OBDII system has detected amalfunction and turned on the MIL to alert the driver. If the vehicles OBD systemhas commanded the MIL to turn on based on a malfunction, the MIL should alsobe illuminated when the engine is running. However, even if the MIL is notilluminated with the engine running, the vehicle still fails because the inspectionsystem shows that the vehicles OBD system tried to turn the MIL on as a result

of a malfunction. The MIL may not be illuminated because of a problem with theMIL itself, or due to tampering with the MIL.

4) More than the allowable numbers of monitors are not ready.

If the vehicles battery has been recently disconnected, or if DTCs have beenrecently cleared with a scan tool, components or systems will be set to notready. This may have been done to temporarily extinguish the MIL for theinspection. The car must be driven to reset the monitors. Some manufacturesadvertise driving procedures while others do not. The vehicle manufacture orqualified service technician is the best source for this information.

5) DLC missing or damaged/communication failure

The reason this may be a failure is because the vehicle could not be testedbecause the DLC is damaged or communication could not be established withthe scan tool. If the inspector cannot locate the DLC, the inspection cannot becompleted. The customer should be directed to the dealership for help in findingthe DLC or getting a valid test.

Until May 1, 2002, vehicles failing the OBD test will be given a two-speed idle (TSI) test.If they fail the TSI test, they must be repaired. After May 1, 2002, compliance with OBDtest will be mandatory.

VEHICLE TEST REPORT

Customer receives a vehicle test report that includes information required by EPA andTexas regulations including the following:

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The MIL illumination check results.

If MIL is illuminated, DTC numbers and descriptions

Readiness results

If the vehicle fails the test, an appropriate alert statement is provided: